1) Two-phase locking (2PL) is widely used for concurrency control in a relational database system. Consider the following schedule for two transactions T1 and T2: S: W1 (X); R2 (Y); R1 (Y); R2 (X); C1; C2 "C1" means transaction T1 commits. For each of the following 2PL protocols: (1) Briefly describe the protocol; (2) State if the protocol allows schedule S, i.e., allows the actions to occur in exactly the order shown in schedule S; (3) Explain the reason why schedule S is allowed or not allowed under the protocol. [15 marks] Basic 2PL Conservative 2PL Strict 2PL 2) Consider two transactions T1, T2 and two data items X, Y. T1: R (X); W (X); R(Y); W (Y) T2: R (X); W (X) Given the following schedule of interleaved operations from T1 and T2: S: R1 (X); W1 (X); R2 (X); R1 (Y); W2 (X); C2; W1 (Y); Al "A1" means transaction T1 aborts, and "C2" means transaction T2 commits. Answer each of the following questions. [15 marks] What type of anomaly occurs in this schedule S? Explain your answer. For each of T1 and T2, insert all the lock and unlock operations to make the transaction satisfy the strict 2PL protocol. Show that modifying the schedule according to strict 2PL can prevent the anomaly. Justify your answer.